Mining: Shortwall vs Conventional Practice Essay Sample

Abstraction
The importance of excavation is decidedly important to human civilisation. In India many of the belowground coal mine operated by conventional bord and pillar system. Main disadvantage of this system is that per centum of recovery is really less. These Looss can be minimized by following shortwall method of working at the clip of pillar extraction. In India some of the belowground mine following this method at the clip of depillaring and per centum of extraction is really high and production rate is besides encouraging. So we should follow this method in all belowground mines where geomining status support.

Keywords
Longwall. shortwall. depillaring.
Introduction:
Mining is the extraction of valuable mineral or any other geological mineral from the Earth. The first excavation operation started at the beginning of human civilisation. Modern excavation operation consists of prospecting of ore organic structures. reserve appraisal. elaborate geological survey. net income computation. ore or coal extraction by any procedure and after the stoping of mining process renewal of the excavation country. Coal/Ore may be extracted by Open cavity or Surface excavation method and Underground excavation method. The different resistance excavation methods used in India for extraction of coal are conventional method i. e. Bord and Pillar method. Longwall method. Shortwall method. Miniwall method etc. In India about 90 % of U/G coal end product is obtained by Bord and Pillar method and hardly about 10 % around by Longwall and other method. Bord and Pillar method is a conventional method but chief disadvantage of this method is that in this method per centum of extraction is really less than other excavation methods because a considerable sum of coal is lost in rib pillar which is left for support during depillaring. But this much loss can be decrease by usage of shortwall excavation method at the clip of depillaring. Bord and Pillar Method:

Bord and pillar excavation method comprises two stages. i. e. . development or ‘whole working’ and depillaring or ‘broken working’ . The phase of formation of a web of roadways is known as development. The coal pillars formed are extracted after the development of mine leasehold and this ulterior phase of pull outing coal from the pillars is known as depillaring. Development of mine consists of driving a series of narrow roads. separated by blocks of solid coal. analogue to one another. and linking them by another set of narrow parallel roadways driven about at right angles to the first set. Fig1 shows the cross sectional layout of bord and pillar. This method is really flexible as initial planning may be modified to cover with any geological perturbations and besides solid coal pillar supports the working country therefore less unreal support are required. But major disadvantages of this method are that per centum of extraction in this method is really less than other excavation method. ( Beginning: Nayak Ram Chandra and Dalai Sangram Keshari. ‘Evaluation of Bord and Pillar Mining System in MCL Mines. 2010. pp 11 )

Different Type of Losses in Bord and Pillar Method:
As earlier said that the major disadvantage of this method is that considerable sum of coal left in the resistance as because different type losingss which are: – * Good sum of coal left in the coal barriers.

* Coal left in the rib pillar during depillaring.
These immense losingss can be lowered down by utilizing of shortwall excavation method at the clip of depillaring. In India most of the belowground mine is developed by bord and pillar method if we adopted this method at the clip of extraction of pillar so we can minimise the immense sum of loss. This method is already adopted in some of the resistance panels which are developed by bord and pillar method. for example-Balarampur longwall and
shortwall. There this method is adopted in 3- 4 panels. Shortwall Mining Method:

This method adopted chiefly at the clip of extraction of pillars which are left at the clip of development in bord and pillar method. Safe and smooth extraction of developed pillar at the mine has been done. The end product achieved is extremely encouraging. The item on public presentation of the first. 2nd and 3rd shortwall panels of Balarampur shortwall and longwall is given below. Table 1: Parameters of 3 degrees

Consecutive no. | Parameters| Achievement from the 1st Panel ( 63L ) | Accomplishment from the 2nd panel ( 58L ) | Accomplishment from the 3rd panel ( 57L ) | Remarks| 01| Total Production from the panel| 89850 Te| 91100 Te| 92605 Te| 1. There is one care and three production displacements. 2. Per twenty-four hours about 6-10 hour of entire 18 hours of production clip is consumed in switching of powered support installed at advanced gallery and positioning with the side of coal rib formed at the advanced gallery. 3. The shearing at the face and shifting of advanced gallery powered support is a cyclic operation. | 02| Period of operation| 30. 12. 07-27. 3. 08| 25. 4. 08-25. 7. 08| 19. 8. 08-11. 11. 08| | 03| Average day-to-day production| 1200 Te/day | |

04| Maximal day-to-day production| 1200 Te/day| 1300 Te/day| 1300 Te/day| | 05| Average day-to-day face progress | 6. 5-6. 7m per day| |
06| Entire face retreat| 540m| 460m| 530m| |
07| Average shear in one shear at the face| 100 Te per shear| | 08| Entire work force at the shortwall panel| 154 person/day ( 58 individuals in care & A ; 32 individuals in each production displacement including executives & A ; supervisors ) | | 09| Percentage extraction| 100 % | |

10| Panel OMS ( including indirect work force ) | 5. 73| 4. 38 ( salving period is included ) | 6. 02| | 11| Face OMS| 10| |
Machine used in shortwall method are Chock shield support/Powered support. Shearer. AFC. Power battalion. Bridge phase stevedore. Crusher and Conveyor belt. Fig 2 shows the layout of shortwall method.

Fig 2: layout of shortwall method ( Source: field visit and field informations of Balarampur Longwall and Shortwall undertaking. 2011 )

Advantages of Shortwall Mining Method:
* In shortwall excavation method whole extraction can be possible. * As it is mechanized method so safety is better than conventional method. * Production rate is really high.
Decision:
Shortwall excavation method should be adopted in all the belowground bord and pillar mines in India holding suited geomining conditions. Although it has a immense capital cost at the clip of following but it is compensated by the cost of recovery per centum and production rate. Mentions:

1 ) Deshmukh. D. J. Elementss of Mining Technology Vol. 1. pp 11. 1-11. 5. 2 ) Singh. R. D. Principles and Practices of Modern Coal Mining. pp 156-158. 3 ) Nayak Ram Chandra and Dalai Sangram Keshari. ‘Evaluation of Bord and Pillar Mining System in MCL Mines. 2010. 4 ) Dey. N. C. ‘Underground Coal Mining’ . 2011.

5 ) Roy. G. C. ‘Underground Coal Mining’ . 2011
6 ) Field visit and field informations of ‘Balarampur Longwall and Shortwall’ . 7 ) hypertext transfer protocol: //www. Google. co. in/url? sa=t & A ; rct=j & A ; q= & A ; esrc=s & A ; source=web & A ; cd=1 & A ; ved=0CCEQFjAA & A ; url=http % 3A % 2F % 2Fwww. worldcoal. org % 2Fbin % 2Fpdf % 2Foriginal_pdf_file % 2Fcoal_resource_overview_of_coal_report ( 03_06_2009 ) . pdf & A ; ei=VAo9UPjjOcrtrQex-IDADQ & A ; usg=AFQjCNEUH4_8QFwqZdin1Atlnxt1MMy5rw & A ; sig2=BioCJy2zl5ZE0xJhgX1vJw [ accessed twenty-fifth August. 2012 ] . ‘The Coal Resource- A Comprehensive Overview of Coal’ . pp 7-8.